Presented is a novel magnetic field modulator made up of permanent magnets, and having a torsional electrostatically driven structure, which was fabricated by electrodeposition and released by KOH solution wet etching. The magnetic properties of the electrodeposited CoNiMnP micromagnets and the torsional angle with respect to the driving voltage of the microdevice have been measured, and the modulation of the magnetic field has been demonstrated. The low power consumption micromodulator, which can achieve a continuous torsional angle of 0°–18° and a pull-in angle of 54.7°, has its own advantage over the traditional magnetic field modulating devices. The novel modulator has not only provided a more effective approach for magnetic field modulation, but also offered a torsional carrier actuator to be integrated with various functional materials or components in many applications.

Vertically aligned silicon nanowire (SiNW)-based resonators were fabricated and utilised to detect aerosol nanoparticles (NPs) by measuring their resonant frequency shifts caused by the additional mass of trapped NPs. Inductively coupled plasma cryogenic dry etching and multiple thermal oxidations are used in the fabrication of silicon nanowire (SiNW) arrays. The SiNWs were coated with gold for contacting to the homebuilt electrostatic NP sampler to collect the flowing NPs. In order to have a dynamic resonance operation in the frequency measurement system, a piezoelectric shear actuator was mounted onto the SiNWs. Examined in a TiO₂ aerosol sampling with a total concentration of ∼8500 NP/cm³, the fabricated sensor exhibited its feasibility as a nanobalance to measure aerosol NP mass at the femtogram level with a mass sensitivity of 7.1 Hz/fg and a mass resolution of 31.6 fg. The NP sampling efficiency of the developed miniaturised NP sampler was found to be three times higher than that of the commercial nanometer aerosol sampler (NAS, TSI 3089). An ultrasonic removal method was used to detach the adhered NPs and further extend the operating life of the sensor.

The check valve micropump can easily reach a high-flow rate, and it has promising application prospects in microfluidic devices and artificial organs. There are several vibrating parts in the check valve pump, including the actuator, membrane and valves. The vibration performances of these parts have a coupling influence on the performance of the micropump. In the work reported in this Letter, four kinds of micropumps with different valves and actuators were designed and fabricated, and the vibration performances of the vibrating parts were analysed by the finite element method. Then, the performances of each kind of micropump were studied by frequency sweeping experiments. The factors affecting micropump performance were determined, and the experimental results approximately coincide with the theoretical analysis. This research provides a theoretical and experimental basis for the design and optimisation of the micropump.

Presented is a process for thin film molecularly imprinted polymer (MIP) coating based on commercial nucleotides adenosine monophosphate (AMP). The compatibility of the MIP film with acoustic propagation and sensor sensitivity for rebinding of AMP have been verified. Thin and porous layers of AMP-based MIP layers were successfully deposited on the sensor surface. Detection tests of AMP have been performed in aqueous media. The sensor response was recorded in terms of frequency and total insertion losses after both steps: AMP extraction from MIP then AMP rebinding. The sensor showed high sensitivity to 25 ppm AMP concentration. The effect of the extraction time on rebinding capacity of the MIP layer has been proven.

In recent years, the emerging bio-chip technology has used external powered pumps for fluidic pumping and mixing. The short-term capillary-driven micromixers with complex mixing structures also showed large potential for mixing devices. This reported work demonstrates the long-term capillary-driven meander micromixer with the planar design, short mixing distance and power-free rapid fluid, transport functions which is compared with conventional syringe pump micormixers. The surface property of various materials was verified by contact angle measurement. Both intrinsic hydrophilic materials of glass and JSR photoresist were good candidates and selected for fabricating the capillary-driven meander micromixer using simple photolithography, laser ablation and low-temperature bonding technology without chemical etching and without the deposition process. The design and simulation of such an effective capillary-driven micromixer have been performed for understanding the geometry effect on flow and mixing behaviour. The glass–JSR–glass capillary-driven meander micromixer can improve mixing efficiency up to over 95% at a short distance of only 8 mm, and has potential for the application of power-free microfluidic chip fabrication and bio-medical examination in the future.

A study is presented of an improved interfacial structure between the electrode and electrolyte of a solid oxide fuel cell. An imprint process, which is considered as a powerful tool to transcribe nano to micropatterns on materials, was employed to imprint fine patterns onto a ceramic sheet of electrolyte. In the presented work, a sheet of ceramic compound material was prepared, and micropatterns were imprinted on its surface. After debinding and sintering, a dense ceramic sheet with fine micropatterns was obtained. To investigate the effect of micropatterns on the overall performance of a fuel cell, three kinds of electrolyte sheets with different surface patterns were employed for this technique. After applying anode and cathode layers, the three fuel cell samples were assembled to test the cell performance. The result was that the finer pattern caused better performance in the three samples by exhibiting the highest overall voltage and power density, and the effective factors of patterns on ion conductivity were discussed as well. Based on the investigation, some further improved three-dimensional microstructures were proposed and fabricated by the method of micro powder imprinting (μPI).

The pMOS-RADFET (radiation field-effect transistor) as a microdosimeter has been widely applied in spacecraft, medicine and personal dosimetry. Thick gate-oxide and zero threshold voltage (V _th) are two critical factors to achieve a high performance pMOS-RADFET. In this reported work, threshold voltage adjustment techniques for a thick gate oxide RADFET by B ⁺ implantation are systematically simulated by Silvaco technology computer-aided design, including implanting energy, implanting dose and annealing conditions. Impurity distributions in gate oxide and silicon substrate are analysed. The results show that the thicker the gate oxide is, the higher the implanting energy and larger dose for tuning V _th to 0 V. Both the annealing temperature and the time have to be as low and as short as possible on the premise of sufficient ion activation.

Overpotential is widely used in electrodeposition of copper nanowires (Cu NWs). However, the value of >2 is harmful for nanowires formation. In this reported study, pulse technology is used to solve the problem. The authors have investigated the effects of potential and voltage mode on the formation of Cu NWs via a porous anodic aluminium oxide template using the electrochemical deposition method. Cu NWs were synthesised by electrochemical deposition in 0.2 M CuSO₄-based solution under different potential modes of direct current (DC) and pulse. Scanning electron microscopy and grazing incidence X-ray diffraction were used to examine the nanostructure, morphology and phase of Cu NWs. The Cu NWs deposited by pulse mode exhibited a high aspect ratio despite a high potential of 2–3 V, whereas that at higher DC potential was rather short because of hydrogen generation in reduction reaction. The hydrogen byproduct during Cu NWs synthesis can be effectively released at the off period of pulse deposition for good nanowires formation.

Thermal-assisted ultraviolet (UV) and H₂O₂-assisted UV photocatalytic oxidation methods utilizing nano-TiO₂ photocatalyst are presented for the digestion of total phosphorus (TP) in water. The photocatalytic experiments for TP digestion were conducted using a 365 nm wavelength UV light, and TiO₂ nanoparticles immobilized on a silicon wafer as the photocatalyst. The effects of H₂O₂ and temperature on the UV photocatalytic oxidation process are explained. The pseudo-first-order rate constants k of two phosphorus compounds for the UV digestion processes were obtained according to the pseudo-first-order equation. Both H₂O₂ and heating could improve the efficiency of the UV photocatalytic oxidation method. But by comparison, the enhancement of heating on the UV photocatalysis process is more distinctly than H₂O₂. In addition, the thermal-assisted UV digestion process will not lead to secondary pollution since no oxidant is needed in this digestion process, which makes it more compatible with electrochemical detection of TP. The thermal-assisted UV digestion method was employed for the digestion of real water samples. Compared with the conventional thermal digestion method for TP detection, this thermal-assisted UV digestion process decreased the digestion temperature from 120°C to 60°C within the same time, which enable the digestion process work at normal pressure.

Reported are the fabrication and thermal stability of an Ru electrode, which is used for a high power Ru–Au contact radio frequency microelectromechanical system switch with a microspring contact design. In this reported work, a new process with bilayer lift-off and a strain release layer is developed, thereby acquiring the 3000 Å Ti/Au/Ru electrode with excellent smooth edges for high-power handling capacity and low loss. Furthermore, thermal tests under 400, 500 and 600°C for over 1 h have been performed. Investigation of the surface with scanning electron microscopy and energy dispersive X-ray spectroscopy shows that the electrode has a good thermal stability at 400°C, which is proper for high-power handling. The cold switch DC current handling capacity is advanced from <90 mA per point (failed) to 100 mA per point (still working).

A multi-resonant capacitive microelectromechanical system switch with wide bandwidth and high isolation has been successfully designed and fabricated for ultra-wideband applications. To achieve high isolation and wide operation frequency bandwidth, three capacitive shunt-connected membranes and meander-shaped inductors with several inductances were utilised in serial connection. Moreover, for achieving a large ‘ON’/‘OFF’ capacitance ratio, a high dielectric aluminium nitride (AlN) film was applied. The measured dielectric relative constant and tangent loss of the AlN film were 8.8 and 0.008, respectively. The capacitive switch has the ‘ON’/‘OFF’ capacitance ratio of 59.6 with the measured capacitances of 52 fF and 3.1 pF at ‘ON’ and ‘OFF’ states, respectively. The three resonant frequencies were formed at 4, 5 and 6.5 GHz, and the isolation performances were over 30 dB at the frequencies ranging from 5 to 10 GHz and 70 dB at 6.5 GHz. The size of the fabricated switch was ∼1.4 × 1.7 × 0.0083 (height) mm³.

The design and development of a field deployable biosensor unit based on InAs quantum dots and a InGaAs quantum well hybrid structure is reported. The detection sensitivity of the sensor unit and in particular the weak light detection ability have been tested and analysed in detail. With a custom-made circuit for signal readout and a data processing unit equipped with an LCD screen for data display, the sensor unit can be used in a centrally managed real-time monitoring system such as for infectious disease management and bio-aerosol monitoring. The high sensitivity of this sensor unit makes it a promising choice for the identification of bio-samples.

Owing to the superparamagnetic iron oxide nanoparticles’ wide applications, a new approach in the synthesis of mainly superparamagnetic iron oxide nanoparticles is reported. The Fe₃O₄ nanoparticles (∼500 nm) were synthesised through the carbon reduction method, which is a brand new method. The best parameters of synthesis of the nanoparticles are fixed through characterising by transmission electron microscope (TEM), X-ray diffraction and a vibrating sample magnetometer of the Fe₃O₄ nanoparticles obtained under different experimental conditions. The TEM characterisation results show that the best ratio of the carbon and ferric chloride is 3:1 and the most suitable heating time is 3 h. The nanoparticles, which were obtained with furnace cooling under vacuum condition after 3 h heating, have the best magnetic properties and most stable crystal from. The characterisations of SiO₂ protected nanoparticles demonstrate that the component of the nanoparticles is Fe₃O₄. The UV–vis absorption spectrum of the Fe₃O₄ nanoparticles demonstrates wide-range light absorption of the Fe₃O₄ nanoparticles. Moreover, quantitative analysis of this new method is conducted to confirm repeatability. The actual qualities of the Fe₃O₄ nanoparticles are always consistent with the theoretical ones, which indicate that the repeatability of this method is excellent.

The soft magnetic properties of Ni₈₁Fe₁₉ films, respectively, composed of Ti, Ta and Cr substrates used for a microfluxgate have been studied in this reported work. The films were characterised using a transmission electron microscope, X-ray diffraction, a vibrating sample magnetometer and a fluxgate solenoid. The testing results showed that Ta substrate film, because of its ladder rising hysteresis loop, is the most appropriate one for the fluxgate core in these four kinds of Ni₈₁Fe₁₉ films, the original Ni₈₁Fe₁₉ film, and the film with Ti substrate takes second place, and the Cr substrate film would not be suitable as the fluxgate core because of its bad soft magnetic properties.

Actuators for objective lens positioning are indispensable components for writing and reading data to and from optical storage media. Significant advances in the technical capabilities of microlens actuators for optical heads have been achieved using MEMS technology, enabling miniaturisation and integration of optical data storage systems. In this reported work, a compact silicon-on-glass (SOG) actuator for two-dimensional (2D) positioning of a dispensed polymer microlens is developed by MEMS technology. A wafer-level process for fabrication of the SOG actuator is achieved using anodic bonding, in which a Pyrex wafer was bonded with an ultra-thin silicon wafer. Dispensed polymer microlenses are fabricated and subsequently integrated onto the 2D actuator by an automatic handling system. Typical displacements of about ±28.6 μm in the tracking direction and 3.2 μm in the focusing direction are experimentally characterised. The compact 2D SOG actuator and assembly technology may be particularly useful for expanding the application area for the optical head.

The use of vibration mode localisation in arrays of micromechanically coupled, nearly identical beam-shaped resonators has been analytically studied for ultra-sensitive resonating-based flowmeters. Eigenstate shifts (amplitude change in this Letter) that are about two times (compared with the single resonator), and orders (compared with the resonator array) of magnitude greater than corresponding shifts in resonant frequency for an induced fluid flow (corresponding to an induced small mass perturbation) are preliminarily obtained by theoretical analysis. When an external force of 100 Pa, corresponding to an estimated fluid flow velocity of about 3.15 m/s, is applied to any one (because of the symmetrical design) of the two coupled aluminium nitride coated single crystal silicon resonators, two orders of the amplitude enhancement can be observed for both the resonators at the higher (second) resonance frequency because of vibration mode localisation, which implies the application possibility to highly sensitive resonating-based flow sensors.

Presented is an improved model of doubly-clamped microelectromechanical systems (MEMS) resonators implemented in very high-speed integrated circuit hardware description language for analogue and mixed-signal (VHDL-AMS). The model includes the effect of residual stress, which may severely shift the resonant frequency of the MEMS resonator from the analytical pre-designed value if the magnitude of intrinsic residual stress is imprecisely predicted. As the stress is not only determined by the fabrication process but also related to the structural dimensions of the resonators, in this work micro-Raman spectroscopy was utilised to measure and characterise the residual stress of a series of fabricated doubly-clamped polysilicon suspended gate field effect transistor type resonators with varying sizes. Combined with the experimentally determined residual stress, the proposed VHDL-AMS analytical model provides an error of < 3.5% resonant frequency shift with respect to the experimental result.

The coupled-resonator-induced-transparency (CRIT) phenomenon in a novel optical resonator system is experimentally demonstrated. The system is composed of a four-ring resonator with a 20 μm diameter on silicon, whose spectrum has a narrow transparency peak with low group velocity. The CRIT effect is observed in the optical coupled-resonator because of classical destructive interference. In this reported work, a CRIT resonance with a quality factor of 7.2 × 10⁴ is demonstrated with the same cavity size and the power coupling of the system is 60%, which agree well with the theoretical analysis. Then, through and drop transmission spectra of the resonator coincide well with each other. Simultaneously, the detuning resonant wavelength can be controlled by changing the temperature.

In this reported work, a femtosecond-laser-based microsolidifying method was employed to fabricate three-dimensional (3D) microsolenoids by injecting liquid metal into helicalmicrochannels in fused silica and solidifying the liquid metal, and a proposed finite element method-3D-vector simulation approach was used to analyse the structure influence. An improved femtosecond laser irradiation followed by chemical etching technology was used to fabricate the complex 3D microchannels, in which an optimal laser power compensation strategy of tuning laser power from 7 to 12 mW was involved. Asilanisation process was carried out before the injection process to facilitate the injection of gallium. 3D numerical simulations of the microsolenoids were carried out by an electromagnetic-coupled analysis method; and a simulation-based co-energy calculation method was used to evaluate the inductance of the 3D microsolenoids. 3D microsolenoids of optimised configurations were then achieved according to the analytical results.

An interferometric displacement detection method of polymer microbeams based on integrated dual-grating was developed for bio-chemical sensing in a liquid environment. Sensing microstructures made of polyimide (PI) with four symmetrically arranged L-shaped beams suspending a central plate were designed and fabricated on a glass substrate using a surface micromachining process. With these structures, deflection changes of the microbeams were transduced to out-of-plane movements of the central plate, which were then measured from the interference of light spots diffracted from the integrated gratings using a charge coupled device image measurement setup. To extend the displacement detection range, two adjacent metal gratings corresponding to a microbeam were formed inside and outside a groove with a depth of 55 nm, respectively, to achieve a phase shift of about π/2 in liquid. The detected noise of aluminium (Al) microcantilevers in ethanol slightly increased compared with that in air, and the noise of PI microbeams in phosphate-buffered saline was about three times larger than that of Al cantilevers in ethanol. The preliminary experimental results in ethanol show that the detection method based on polymer microbeams integrated with dual-gratings is feasible in a liquid environment. Antibody–antigen binding detection was also conducted with a rabbit immunoglobulin G (IgG) immobilised chip in 100 μg/ml goat anti-rabbit IgG solution.

Planar lithography techniques are not effective for precise fabrication of microdevices with hemispherical shapes. Drop-on-demand (DOD) inkjet printing (IJP) of photo-curable ink is a more appropriate fabrication approach as it takes advantage of the surface tension as well as of the delivery of a well-defined ink volume. Described is a DOD IJP technique onto geometrically-patterned silicon substrates enabling the controlled fabrication of SU-8 hemispherical microcapsules. Open half capsules of 100 µm in diameter with inner cavity volumes of 5, 20 and 45 pl with a printing yield above 96% are demonstrated. The same technique is directly adapted to the fabrication of microcapsules embedding silicon microchips. The reported findings open new paths for controlled encapsulation of liquids into smart microsystems.

In this reported work, nanosphere lithography (NSL) and inductively coupled plasma reactive ion etching (ICP-RIE) are combined to successfully fabricate a sub-wavelength structure (SWS) on a glass substrate, achieving broadband antireflection and increasing the transmittance of incident light through the glass. The experimental results show that the SWS surfaces with 180 nm width and 50 nm height could be fabricated onto glass. The mean reflectance of a blank glass is 5.81% in the wavelength range of 400–950 nm, 3 min of ICP-RIE combined with NSL reduce the mean reflectance to 3.5% and increases the mean transmittance from 92.3 to 94.3%. An additional coat of a 200 Å-thick gold layer on the 30 s etched surface sample reduces the transmittance in the visible light range (400–700 nm) to 36.6%, which is 2.25 times larger than that at the infrared range (700–950 nm). The proposed novel fabrication technology has the advantage of being low cost, and the fabricated nanodot array structure, which is gold coated, can be used on an insulated window.

The nanoscale manipulation of 1D soft and flexible ‘DNA origami nanotubes’ (DONs) that are 6 nm in diameter and 400 nm in length, and placed on a mica substrate in a TE/Mg²⁺ buffer solution, was executed by an atomic force microscopy (AFM) tip using a programmable tapping-mode manipulation strategy. The AFM's tip tapping amplitude was controlled to be less than or equal to 10 nm while vibrating in a solution with Mg²⁺ concentration of 10–20 mM. A series of single-point and one-step manipulation experiments revealed that manipulation can be achieved with an 80% successful rate under the condition that the AFM tip vibration amplitude is 3–4 nm and the Mg²⁺ concentration is 10 mM. Utilising this optimised condition, multipoint and multistep manipulation based on the programmable tapping-mode AFM process was conducted and nanomanipulation of DONs was successfully demonstrated.

A light-emitting diode (LED) is a novel electronic light source that provides a direct conversion of electrical energy into light. A typical LED power package has a heat flux of 100 W/cm², thus high power LEDs face severe thermal challenges because of their small size and general lack of a proper thermal path. The advantage of microheat pipes (MHPs) which are largely used in heat dissipation of microdevices is based on phase change. With the trend of using a silicon wafer as the substrate in LED manufacturing, a silicon-glass MHP was fabricated for the quick spread of heat from the LEDs. Flat plate grooved MHPs are introduced. The grooves were fabricated on the silicon wafer and followed by bonding with Pyrex 7740 glass. Water was selected as the working liquid and the charge rate was 40%. The temperature test experiments were carried out to test the feasibility of the MHPs in LED heat conduction, and the preliminary experimental results indicate that the heat conductivity of MHPs without a vapour chamber is better than that of MHPs with a vapour chamber, which is even better than that of the silicon wafer.

Presented is the design, fabrication and characterisation of an electrostatic-driving and capacitive-detection differential resonant pressure microsensor. The differential structure consists of two resonators immobilised on the diaphragm. In response to the pressure under measurement, the diaphragm deflection increases the intrinsic resonant frequency of one resonant beam and decreases the resonant frequency of the other. A differential frequency output reduces the common frequency drift caused by stresses and interferences, and thus improves the sensor's stability. The device geometries were optimised using numerical simulations and the fabrication process was based on a silicon-on-insulator wafer requiring only two masks with simplified microfabrication steps (e.g. sputter, wet etching and deep reactive ion etching). The sensor was quantified in an open-loop characterisation platform, producing a quality factor higher than 10 430 in vacuum ( < 0.5 Pa). Closed-loop test results recorded a linear resonant frequency shift (a linear correlation of 0.9999) in response to applied pressure, with a sensitivity of 227 Hz/kPa. This resonant pressure microsensor has a simple fabrication process and reliable performance, and can be used for pressure monitoring in various locations including weather stations and aerospace.

An electrostatically driven valveless micropump with a peristaltically moving membrane for gas chromatography is presented. The one-chamber micropump has a peristaltically moving membrane formed by polyimide with four electrodes used to separate the single chamber into four pump chambers. For a peristaltically moving membrane, several dielectrics were tested for their ability to endure high-voltage breakdown, and the PI-2545 polyimide was finally chosen to reduce the operating voltage. After testing a single-sided micropump (SSM), a double-sided micropump (DSM) was fabricated to enhance pump efficiency. Theoretically, the flow rate of the DSM is quadruple that of the SSM, and the electrodes in the membrane can recover from the motion of pulling down and pulling up with ease. To verify the peristaltic motion of the micropump, a transparent indium tin oxide (ITO) electrode was used. An ITO–ITO micropump was fabricated, and to measure flow rate, an ITO–Si micropump was fabricated as well. The micropump was fabricated on a glass substrate with ITO and on a silicon substrate with a polyimide membrane. A maximum flow rate of 27.19 µl/min was measured at 4 Hz and 100 V DC. The micropump was operated by four electrodes with a four-phase sequencing actuation.

Microelectrodes used in dielectrophoresis (DEP) chips are mostly made of metal materials; however, the metal electrodes can induce extra background noise as observed in a fluorescence microscope. Currently, the fluorescent response still dominates the indicators of immunoassays; therefore it is important to eliminate the extra background noise of the fluorescence response generated by metal electrodes for an immunosensor. In this reported study, a transparent conductive material, indium tin oxide (ITO), was employed in the fabrication of DEP electrodes, and the fluorescent responses of a DEP chip with transparent electrodes were compared with an identical DEP chip with conventional Au electrodes during an immunoassay. According to the experimental results, the enhancement of the fluorescent response of the DEP chip with ITO electrodes was greater than the values of the DEP chip with Au electrodes; about 1.57 times and 1.44 times for the immunosensing of 10 and 1 nm bovine serum albumin (BSA), respectively. In addition, by applying the DEP force during the immunosensing, the fluorescent response was also enhanced because of the condensation ability to BSA by the DEP force. Consequently, a DEP chip with transparent ITO electrodes and a microcavities array has been demonstrated, and the background noise of the fluorescence response can be eliminated to enhance the sensitivity of immunosensing.

The detailed design and analysis of a polarisation mode splitting resonator based on a silicon-on-insulator rib waveguide are presented. By analysing the mode birefringence in the ultra-small rib waveguide, the directional coupler is introduced to the microring resonator to realise the splitting of the quasi-TE and quasi-TM polarisation modes from the same output port for a specific wavelength range. It is demonstrated that after splitting the quasi-TM polarisation mode, the Q-value of the quasi-TE polarisation mode is about 2.3 × 10⁴, almost twice of that without splitting the quasi-TM polarisation mode. This novel characteristic of a race-track resonator allows it to obtain single polarisation mode at a specific wavelength by itself. This characteristic makes a contribution to accurate wavelength selection, which has been proved to be very useful in the dynamic testing of electrooptical modulators and quite promising in many other applications of optical components.

A catalytic combustion hydrogen sensor has been fabricated using the microelectromechanical system technology. The application of hafnium oxide thin films as the insulating layer has been deposited by electron beam evaporation. The semiconductor combustion catalyst tin oxide layer was prepared by chemical vapour deposition. It is a novel application of semiconductor material to a catalytic combustion gas sensor. The resistivity of hafnium dioxide thin film is about 3 × 10¹² Ω cm at 900°C. Both the sensing elements and the reference elements could be connected in a suitable circuit such as a Wheatstone configuration with low power consumption. The catalytic combustion sensor shows high response to hydrogen at an operating voltage of 4 V and has a higher relative sensitivity and a good linearity for concentrations of hydrogen ranging from 0 to 4% in volume. Good consistency and high accuracy of the micromachined catalytic combustion gas sensor were achieved.

Membrane proteins embedded in bilayer lipids of cell membrane have unique functions including inter-cell communication and ionic/molecular transport. To understand the structure and function of the membrane protein embedded in a native biological bilayer lipid environment is a major research area in biology. A reconstitution/crystallisation process of membrane proteins and lipids can form virus-like nanoparticles, and have important potential applications in drug design and drug delivery. Earlier studies used a standard dialysis process that is inherently low-throughput, time consuming (days to weeks) and costly in protein materials. In this reported work a new microfluidic device is demonstrated to rapidly form membrane protein lipid nanoparticles in an extremely short period (seconds). The reconstitution process occurs using a continuous flow dominated by convection-diffusion phenomena in the microfluidic channel, which can form protein/lipid nanoparticles using only nanolitres or picolitres of protein sample. Moreover, a controllable syringe pump is used to test a combination of conditions, rather than using inefficient hand pipetting. Therefore this novel microfluidic device has an ability to rapidly form uniform membrane protein/lipid nanoparticles, and the authors believe that this new method will make a transformative impact on commercial applications in a variety of areas from biology to pharmacology.

Presented is a process for fabricating suspended magnetic polymer structures with SU-8 photoresist dispersed Fe₃O₄ nanoparticles. By controlling the exposure doses of ultraviolet (UV) is shown light, floating structures are patterned during the first UV exposure and then the anchor structures are patterned at the second exposure. It is shown that suspended magnetic polymer structures, such as doubly-clamped beams, can be successfully fabricated and released using a single development process. In addition, the functionalities and characteristics of these magnetic doubly-clamped beams are demonstrated and discussed. The resonant frequencies of these structures were measured under a sinusoidal magnetic field at an amplitude of 10.37 mT; the frequencies for structures 5 and 6 mm long were 5.21 and 4.18 kHz, respectively.

This letter studies the surface heat convection of thin graphene sheets and the application of graphene wires as nanoscale flow and temperature sensors. Graphene wires with relatively large length-to-width ratios were designed and fabricated using bi- and few-layer graphene sheets. Prior to testing, the devices were packaged in a microfluidic chamber with capillary tubes as upstream and downstream connections to minimise environmental interference. The thermal inertia of the graphene wire was studied at 70°C and the flow sensing behaviour of the device was characterised by monitoring normalised resistance changes at different flow rates. The authors experimental results demonstrated the negative temperature coefficients of the bi- and few-layer graphene films. Moreover, the flow sensing resolutions of ∼ 0.07 l/min and 0.1 l/min were achieved from the bi- and few-layer graphene hot wires, respectively. The temperature sensing behaviour of the graphene thermistor was studied in a small temperature range from room temperature to 80°C. The larger negative temperature coefficient of the bi-layer graphene resulted in a higher sensing response than the few-layer one.

Presented is an animation of the sporangial motion for making bionic tail actuators of flapping microair-vehicles regarding energy saving. A SUS-304 steel foil 40 μm thick is used as the working substrate. The actuation area of the 40–50 comb-shaped cantilevers is designed to have maximum actuating angle change around the order of several degrees. An Nd-YAG laser cutting is performed to machine the surface tension-driven actuator. Surface modification including parylene coating and oxygen plasma treatment are added to enlarge the actuation stroke angle by up to 10°–12° for practical usage in flight control.

The fabrication of a superhydrophobic surface by texturing of the polytetrafluoroethylene (PTFE) surface in the form of pyramidlike structures is demonstrated. In addition, the superhydrophobic surface is duplicated by using a polydimethylsiloxane (PDMS) mould. The hydrophobic properties were determined by measuring the contact angle and roughness of the PTFE surface on the pyramidal structure. The calculated roughness factor and root mean squares roughness ranged from 2.47 to 2.6 and 0.25 to 0.4 µm, respectively. The contact angle of a water droplet on the PTFE surface was greater than 150°, which was well maintained for over seven weeks. In the case of PDMS mould surface, the contact angle of a water droplet was greater than 130°.

With the assistance of polyvinylpyrrolidone (PVP), PbS single crystalline nanosheets with large size (5–25 μm in diameter) were synthesised via a hydrothermal route. The nanosheets presented shapes of four-horn, square or rectangle. Nanosheets with a zigzag edge were also found in the products. By adjusting the reaction parameters, dendritic or flower-like PbS microcrystals could be obtained. The formation of nanosheets should be a result of the cooperation effect from PVP, thiourea and solvent. X-ray diffraction, a scanning electron microscope, a transmission electron microscope, high-resolution transmission electron microscopy, selected area electron diffraction and Raman spectra were used to characterise the products. A possible growth mechanism for the microcrystals is also discussed.

Presented is a cavity-first approach for producing released microelectromechanical system (MEMS) structures from the front side of a silicon on insulator (SOI) wafer. This approach shows excellent process compatibilities to CMOS and is significantly valuable to MEMS–CMOS monolithic integration. In this approach, prior to metal layer deposition and other components fabrication, which are easily damaged by vapour-phase hydrofluoric (HF) acid, release holes with a diameter of a few micrometres were created in the active silicon layer, and the cavities were formed after removing the underneath SiO₂ box layer by vapour-phase HF etching. An amorphous fluoropolymer thin film was then successfully introduced to refill those release holes without entering into the cavities, after which the wafer can be fabricated by standard process with negligible surface fluctuation. Finally, MEMS structures were released from the front side of the wafer by inductively coupled plasma reactive ion etching (ICP-RIE). This approach enables monolithic integration of MEMS with CMOS circuits on SOI wafers with easy-package capability, eliminates the requirements on device release by wet chemical etching or ICP-RIE from the backside of the wafer and reduces the risk of device damage by vapour-phase HF etching. This approach also excels others in simplicity and high yields with better thickness uniformity and less residual stress in a MEMS structure.

Pd nanoparticle (NP) modified glassy carbon electrodes were prepared by the electrochemical deposition method of cyclic voltammetry (CV) and the potentiostatic technique, respectively. Scanning electron microscopy was used to characterise the morphology of the NP-modified electrode's surface. The electrocatalytic oxidation of formaldehyde and formic acid were investigated at the modified electrodes by CV and linear sweep voltammetry. The experimental results show that the electrodes display remarkable electrocatalytic activity and long-term stability for the oxidation of formaldehyde and formic acid. The oxidation mechanism of formaldehyde and formic acid on the modified electrodes is discussed primarily. The experimental parameters were optimised for establishing the methods of formaldehyde and formic acid determination. The oxidation peak current is linearly proportional to the concentration of formaldehyde in the range of 1.0 × 10⁻⁴ –1.4 × 10⁻²M with the detection limit being 3.0 × 10⁻⁵M and relative standard deviation (RSD) being 3.9%. The linear dynamic range of formic acid is in the range of 1.0 × 10⁻⁵–1.0 × 10⁻² M, the detection limit is 4.0 × 10⁻⁶ M and the RSD is 2.8%. The low detection limit, wide linear range and high sensitivity of the sensors make them valuable for further application.

Presented is a structural investigation of silicon nanowires, which is conducted with grazing incidence small angle X-ray scattering. The morphology of the wires is analysed following experimental measurements. Three diameters (50, 100 and 200 nm) are investigated in relation to the aspect ratio of the wires (length 25 µm). Periodic fringes because of the weak distribution of the diameter are observed on the experimental images. The asymptotic behaviour of the scattering signal along the q_y direction is also analysed and presented.

Fabrication of nanopillars via anodised aluminium oxide (AAO) serving as a template is cost-effective and widely used. However, control over the length of nanopillars by this method remains a challenge. Presented is a two-step wetting method to fabricate polymer nanopillars of controlled length using a poly(dimethylsiloxane) (PDMS) filled AAO template. Firstly, by filling uncured PDMS into the nanopores of AAO and then dissolving partially, the depth of the nanopores is adjusted and increases with the dissolving time. Subsequently, the second wetting step by polymeric liquid with the PDMS filled AAO template yields length-controlled nanopillars. Nanopillars of different lengths and different polymers are fabricated using this method via both melt capillary infiltration and solution wetting. It is also demonstrated that the PDMS filled AAO templates in the presented method are reusable. This method is simple, cost-effective and may facilitate applications of polymer nanopillars of controlled length.

This Letter describes the implementation of a droplet-based protein chip with an Ni–Co alloy layer for conducting immunoassays. The proposed chip consists of a substrate of a printed circuit board and a microchannel layer. On the substrate surface, an Ni–Co coating was fabricated by electrodeposition to immobilise the histidine-tagged protein. Through droplet fusion and mixing, the fused droplets aligned at the downstream position of the microchannel and were immobilised by the Ni–Co layer for further incubation and fluorescence detection. The experimental results showed that the sample which is encapsulated by the carrier fluid does not have evaporation and contamination problems. Therefore strong fluorescence intensity proportional to the sample concentration can be obtained. The fluorescence intensity is also related to the droplet size. An extremely low concentration of encapsulated content in a smaller droplet might result in arduous fluorescence detection. This proposed droplet-based protein chip allows the operation sequence of the immunoassay to be conducted automatically through the manipulation of droplets. Moreover, the fabrication process is simple and the chip can be implemented to immobilise any functional proteins with His-tag attached.

The nylons functionalised with single walled carbon nanotubes (SWCNTs) at pH 2.5 and 3.5 display the time dependence of the water droplet contact angle, which is attributed to the adsorption of water molecules onto the nylon–water contact surface and the consequent increase in surface free energy. The contact angle of nylons functionalised at pH 4.5, 6.5 and 8.0 varies marginally with contact time, presumably owing to the presence of a large amount of SWCNTs on the nylon surface. Using the obtained nylon as a flexible electrode, an electrowetting on a dielectric system is designed. The contact angle decreases with the increase of the applied voltage and the electrowetting response is sensitive to the surface free energy of the water droplet. A low surface free energy is preferable for actuating the movement of the water droplet at a low-driving voltage.

The effects of phosphorus doping on the bending strength of a single crystal silicon (SCS) microbeam are reported. First, a specially designed bending microstructure test and a simple bending test device are presented. Secondly, the results of bending strength tests for six groups of specimens with different phosphorus doping concentrations are presented. The test results are comparatively analysed using a Weibull distribution, revealing that the bending strength has a monotonically increasing relationship with the phosphorus concentration. The effect of surface roughness on the bending strength is also investigated. Finally, the mechanism underlying this phenomenon is demonstrated. The results indicate that the bond strength of a phosphorus–silicon pair is larger than that of a silicon–silicon pair, and the phosphorus atoms increase the energy necessary to create new surfaces. Therefore more energy is required to fracture the microbeam, and the fracture strength increases. Research on this topic therefore shows some practical significance for improving the bending strength of a SCS microstructure.

Surface passivation is a general approach to enhance the luminescence of small-scaled size upconversion nanomaterials. In this reported work, a two-step hot-injection method was developed to synthesise core/shell structured NaYF₄. A transmission electron microscope, X-ray diffraction and X-ray photoelectron spectroscopy were employed to prove the successful fabrication of β-NaYF₄:Yb, Er at β-NaYF₄. Core size and shell thickness were controlled by the amount of stabiliser and precursors addition, respectively. The upconversion efficiency of the resultant core/shell structured nanocrystals could be improved more than a 100-fold by comparison with the original core nanocrystals. Significant fluorescence enhancement was ascribed to the successive injection of precursors at elevated temperature.

Maskless and low-destructive nanofabrication on quartz surface can be realised by friction-induced selective etching. In this reported work, the effect of scan parameters and etching temperature on low-destructive nanofabrication of quartz was studied. It was found that the etching thickness increased with the increase of the scan load and the number of scan cycles, but decreased with the scan speed. The wear of quartz did not help to increase the etching thickness. To limit the possible destruction, the scanning should be finished under low-destructive conditions. Compared with single scanning under high load, repeated scanning under lower load was more beneficial for fabricating a deeper structure in a low-destructive way. To improve the fabrication efficiency, faster scan speed and higher etching temperature were the preferential selection. Based on the optimisation of the fabrication parameters, various styles of nanostructures can be produced on the quartz surface. These results will help realise the controllable low-destructive nanofabrication on quartz.

Molecular dynamics simulations were performed to investigate the wrinkling deformation of one single-layer graphane (GA) sheet under shear, and the shear deformation was compared with that of the macromembrane under shear. Furthermore, the thermal conductivity of the wrinkled GA sheet at 300 K was calculated. Moreover, the differences of anti-shear capability and thermal conductance between the GA and another corresponding graphene sheet are discussed. The results show that the solutions of the macromembrane are applicable to predict the wrinkling deformation of the GA sheet under shear and that both the GA and the graphene sheet under shear have comparable anti-buckling capability, whereas the GA sheet has much lower post-buckling load-carrying capacity. By increasing the shear strain, the thermal conductivity of both the GA and the graphene sheets decreases, and under the same shear strain the graphene sheet has higher thermal conductivity than the GA sheet.

Nickel hydroxides (Ni(OH)₂) with various morphologies, including flower-like, walnut-like and particle-aggregated microspheres, have been successfully synthesised by a surfactant-assisted microwave hydrothermal method. NiO microspheres have been obtained by calcining corresponding Ni(OH)₂ precursors at 400°C for 2 h. The products were characterised by X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy and transform electron microscopy. The electrochemical properties of the NiO microspheres with different morphologies were also investigated.

The effective visible-light-driven photocatalysis of tetracycline still remains a big challenge for scientists. In this reported work, TiO₂/Fe₂O₃/CNTs (carbon nanotubes) have been successfully synthesised by a fast and convenient method for the first time. A wide range of techniques, such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, magnetic measurements and UV–vis absorption spectroscopy were applied to characterise the obtained TiO₂/Fe₂O₃/CNTs. Moreover, the photocatalytic properties of the TiO₂/Fe₂O₃/CNTs in the degradation of tetracycline have been studied. In addition, it was found that TiO₂/Fe₂O₃/CNTs have a better reusable photocatalyst than other traditional photocatalysts by the magnetic separation recycling method.

Focused research efforts on enhancing the sensitivity of piezoresistive MEMS pressure sensors have been made in the past. Most of these techniques applied to enhance sensitivity have depended on manipulating the geometries of the diaphragm, selection of the diaphragm material and improving the piezoresistive properties. Piezoresistors change their resistance linearly proportional to the bending stresses induced in the diaphragm on application of the pressure. Therefore the successful design of a high sensitivity piezoresistive pressure sensor totally depends on the efficiency with which the induced stresses are harvested in the transduction process. Introduced is an innovative way to harvest the maximum stresses. The dual Wheatstone bridge implemented with eight piezoresistors effectively converts the XX and YY plane stresses into electrical voltage to double the sensitivity. The simulation experiment results show that the sensitivity of the 91.72 µV/V/kPa with ensured linearity over 0–14 kPa using a 5 µm-thick diaphragm with a single bridge can now be achieved by employing a 7 µm-thick diaphragm with double Wheatstone bridges but with excellent linearity extended over 0–54 kPa. Almost the same trend is seen between the 3 and the 5 µm-thick diaphragms. Thus, this technique paves the way for achieving large voltage sensitivity bundled with a high level of linearity over a wide pressure range by using thick diaphragms.